Issue 140

Update: SJ-21 & SJ-25

4 Mar 2026: SJ-21 (49330) and SJ-25 (62485) remain separated by ~560-640km with SJ-21 located to the east of SJ-25. The two orbits are plane-matched and the vast majority of the separation in-track. We may beginning to see a new pattern of life for both satellites. SJ-25 decreased its SMA ~5.4km on 5 Feb. About a week…

4 Mar 2026: SJ-21 (49330) and SJ-25 (62485) remain separated by ~560-640km with SJ-21 located to the east of SJ-25. The two orbits are plane-matched and the vast majority of the separation in-track. We may beginning to see a new pattern of life for both satellites. SJ-25 decreased its SMA ~5.4km on 5 Feb. About a week later, SJ-21 decreased its SMA 3.1km. On 2 Mar 2026 SJ-25 again decreased its average altitude, this time ~7.3km. It will be interesting to see if SJ-21 follows with a similar maneuver in the coming days.

SJ-21/25s’ recent maneuvers are likely station keeping and not indicative of any renewed proximity operations. The satellites remain co-planar with in-track separation. A reminder that in-track maneuvers are by far the least expensive in terms of energy (fuel). Should Chine desire to do so they could quickly and cheaply return to RPO conditions between these two satellites.


Update: SJ-21 & SJ-25

2 – 7 Mar 2026: Total/Radial/In/Cross-Track (TRIC) Plot Showing Distances Separating SJ-21 and SJ-25. Note Minimal Radial (0-10km) & Cross Track Separation (0-0.5km). In-Track Separation is 560-640km.
(saberastro.com)


4 Mar 2026: SJ-21 and SJ-25 Orbits over ~127°E
(saberastro.com)


Update: TJS-3 & TJS-10


1 Feb – 4 Mar 2026: Orbital History for SJ-21 (left) and SJ-25 (right)
(celestrak.org)